If a tree falls in the forest and no one is there, does it still make a sound?

Jehookah Jarmon, Gorvenstof, Ukraine

It makes the sounds of branches snapping and the almighty thump when the trunk hits the hard ground.
Sound is sound and doesn't rely on people to interpret it.

Jack Hill, St Albans, England

Only if it's a hoary old chestnut like this one!

Alan Williams-Key, Madrid, Spain

Yes. And isn't that a rather arrogant question, as what about all the animals that presumably hear it?

Allan Fraser, Darlington, England

It depends on what you mean by 'sound'? The air waves would still vibrate but without an ear/listening device to receive them there would be no sound.

Conaldo, London, UK

Sound is something within human experience. Outside of this it's just air (or whatever other medium) vibrating. If someone is there to hear it, it makes a sound, if not, it causes rapid movement of particles.

Seth, Edinburgh, Scotland

I've always thought the point of this question was: if there's no way to establish whether there was a sound, then it ultimately doesn't matter. In fact, you could say that the definition of a sound is its detection, rather than the physical phenomenon. Of course, once we develop an instrument that can detect vibrations we couldn't otherwise hear, a previously non-existent sound comes into being.

This is a profound question with ethical connotations. For example, if we are unaware of somebody's suffering, does it exist? We can only be aware of it if they tell us or we infer it from our common humanity. But suppose vegetables suffered when we picked them, but had no way of telling us so. We might discover a vegetable nervous system, but we wouldn't know if the nerve-signals represented pain, information or something we have no conception of. The sensible conclusion would be to save your subscription to the Vegetable Liberation Front.

Tom Boddington, Leeds, UK

Yes, of course.

Allan Fraser, Darlington, UK

Well i suppose it comes down to God and the imagination, if all is imagined then no, because the tree had not been imagined in the first place. If there is a God, or by some miracle we simply exist, then yes, because as i suspect and hope, we humans are not the centre of the universe. An infintismal amount of happenings are occuring without our knowledge or interpretation.

Luke Van Opstal, Sydney Australia

My guess is that it makes compression waves in the air that could be interpreted - with the right biological equipment - into sound.

Jason Gaskell, Newcastle, England

No it doesn't. Sound is the product of our ears. If there are no membranes (ears, microphones etc) to vibrate then there is no sound.

Darren, Lancaster, UK

Define 'sound'. When the tree hits the ground, its kinetic energy will be partly transferred into vibrations in the air called 'sound waves'. If these come into contact with a sensitive membrane such as an ear-drum and are then interpreted by a brain (human or otherwise), they will be experienced as what we call 'sound'. Although the sound-waves have an objective existence, I suppose that strictly speaking they are not 'sound' until they are subjectively interpreted by a brain. Still the way the question is framed is a bit anthropocentric - if the sound waves caused the ear drum of a passing bird or squirrel to vibrate, what they would experience is presumably also called 'sound'- though it is possible it would not sound quite the same as it would to a human.

Steve Fitzpatrick, London, UK

The traditional answer is that it makes a sound but not a noise - noise being a subjective judgement.

However Quantum Mechanics gives us the Observer Problem. Basically this means that as all events are essentially random (on a sub-atomic scale), until they have been observed we can't be sure they've actually happened.

So strictly the tree can't actually be said to have fallen down until it has been observed lying prone. It just exists in a half-and-half state where, like the Duke of York's men, it is neither up nor down.

The noise also exists in this ghostly state (and so did this post until you read it).

Martin Porter, Glossop, Derbyshire

The short answer is yes, inasmuch as sound waves are propagated.

Fragano Ledgister, Atlanta, USA

Of course it does.
The idea that a member of the human race has to be present at any occurrence for it to be true is quite ludicrous.

Sounds are being created all over the world which are never
heard by humans and as a final straw there are supersonic sounds which are beyond the range of the human but can be heard by other creatures such as bats.

Jack Hill, St Albans, England

The vibrations will not go unnoticed forever because a falling tree impacts dramatically on the environment around it, perhaps setting aflutter the very butterfly whose wing fannings led to Katrina which led to the deafening outcries for reform in disaster preparedness.

Steve, Kansas City, USA

An even older corollary to this "If a man speaks and there isn't a woman to hear him, is he still wrong?"

Peter Cranny, Liverpool, UK

The act of observing something changes the nature of that very same thing.
Now of course you can object, like Einstein: "Do you mean to tell me the moon isnt there until you look at it?" ... but nevertheless ... Quantum theory does seem to lead to the conclusion that reality or existence or whatever you want to call it, is not observer independent.

David, Florence USA

Yes it does. If you ARE around to here it, it would make a sound. So when you're not around to here it, it would make a sound. If you don't believe that, put a recording device near a tree that's about to fall and then go away. If the tree doesn't already smash the recording device, listen to the sounds on the tape for proof that it does make a sound.

Joe Nossote, Reno, Nevada, United States

This is only a 'conundrum' if one is guilty of logical equivocation. If one defines 'sound' as a vibration in the air, then the answer is 'yes'; if one defines it as a perception of some kind - say, involving the human ear and brain - then the answer is 'no.'
As with anything else, if you're clear on the meaning of your terms such questions become decidable; if you equivocate between two meanings, they remain 'paradoxes' (though spurious ones).
Here's a comical equivocation on the word 'some' that should make the point clear. Some dogs have fuzzy ears; my dog has fuzzy ears; therefore, my dog is some dog! (Moral: don't equivocate)

Mark Kennedy, Toronto, Canada

What if you can't hear the wood for the trees?

Matt, Cardiff Wales

It strikes me that all the answers so far give rise to a more interesting question - why does the number of answers to an item in N&Q vary in inverse proportion to its importance!

Paul Thompson, Perth Scotland

Imagining that there is sound out there in the universe is the same as believing that colours exist. Sound and colours are the result of the brain interpreting the waves that hit the ear or the eye. If there is no eye or ear around (or other organs of living creatures that can perceive them) there are no sounds or colours.

N Beckett, Krefeld, Germany

Yes even if there were no humans animals or insects around God would hear it. God is everywhere and knows everything.

Patricia, St Charles, Mo US

Common sense tell as that all things exist whether we are there or not to experience them; otherwise we wouldn't bother going on holiday in case our destination is not there. Common sense also must tell us that vibrations are not sounds until our ear and brain interpret the vibrations into understandable or enjoyable information we need to survive.

bill, london england

What length of beard makes me unattractive to the opposite sex? Any of the above would qualify.... Get out more ... or look at yourself retrospectively

Professor Knob, Oxfordshire Oxford

It does becaus it makes a vibration

Ben Hawksworth, Nottingham, England

If no consciousness was there the probability wave did not collapse so it never fell.

Stephen, Oxford Oxon

If no one is around to perceive it then there is no tree, there is no forest and there is no sound.

Jarrod, Sydney Australia

Yes, it does. The world and beyond are greater than one's perception, which is limited.

Marcia, Birmingham, England

"If a tree falls in the forest with no ears to hear does it make a sound.
It matters not for the tree has fallen."
Westerners should avoid Eastern philosophical queries. The riddle of the tree is ancient and ask not of sound but of loss in nature.

Shana Vasquez, Dubuque USA

Okay, I've heard enough on this topic now. Or did I? :)

Richard, Maidenhead, UK

If no one is there, there is no forest.

Thaddeus Morling, London, UK

"IF" implies it hasn't happened therefore, there is no sound.

Jeannie, Queens USA

I cannot believe this question is even taken seriously, and yet it is. Of course the falling tree makes a sound, whether it is 'heard,' or not!
The ear, does NOT create sound, it is only able to transmit sound; the eardrum reacts to the sounds around it, that are of sufficient strength to cause it to vibrate; the ear does NOT vibrate to cause the sound of the tree falling, quite obviously.
Put on a good pair of earmuffs, and then snap a piece of wood, or smash a plate, whatever you want, and ask yourself, would you have heard it if it hadn't been for the earmuffs?
The sound waves were formed, but prevented from activating your eardrum, by the earmuffs, but nevertheless, be honest with yourself, you know the sound waves were created, and you know you would have heard them if it hadn't been for the earmuffs. If you have broken a piece of wood in your hands, you would have felt the shock-wave that creates the sound, within your very hands.
Look at that aeroplane flying above you at 14,000 feet, you cannot hear it, for the sound waves dissipate before they reach your eardrum, yet you know jet engines make huge amounts of noise when they work, and if they were not working, and therefore making noise, then the aeroplane would not be flying - you know all these things!
You may not be able to hear the aeroplane because of the distance between yourself and it, but you know the sound is there, you know it is being made, completely independently of your hearing.
Sound does not depend upon you hearing it, you hearing sound, depends upon your proximity to the source of the sound, the cause.
Your ear does not create sound, your ear reacts to sound, to conduct it to your brain, and make you aware of its presence.
Does the falling tree make noise, yes, every time.

David, Devon

Yes it does make a sound. But my old teachers told me it didn't.

Samuel, Christchurch New Zealand

When the tree falls in the forest, sound waves are generated that impinge on your eardrum if you are there. The sound waves are processed by your cochleas and neuronal signals are transmitted to your auditory cortex. The action potentials from the nerves from your cochleas act on the auditory cortex to produce the perception of sound. Therefore the sound is the response of the neurons in your auditory cortex. Any creature that has the perception of sound will hear the sound of the crash. There is no sound in the sound waves themselves. The sound is produced by the action potentials and synapses and only registers as sound if the action potentials reach the auditory cortex. The same situation exists for all our senses. Our entire perception of the world we live in comes to us through the action potentials in the nerves that reach the cortex in our brains. You never actually see the world first hand but only through the interpretation of the action potentials and synapses in the neurons in the cortex that come from the nerves from our senses. You register the result as your perception of the world that we live in. The confusion results when people assume that the sound waves are the sound.

David W-Smith, Adelaide, Australia

It does not. There is no ear involved therefore "sound" does not exist.

Rhonda, Pittsburgh USA

This is a philosophical as well as a scientific question. Scientifically, the answer would be yes. Just because there is no one in the forest to hear the sound does not mean that the sound did not take place. If once places a tape recorder in the forest, then later plays the recording after a tree fell, then we know that the sound occurred.
Another way to address this would be to consider a blind person standing outside. The blind person does not see any light, so does that mean that there is not daylight? Does one have to be sighted for there to be light? No. Light is a form of radiation. It is visible to most people, but not to everyone. So if no one is in a vacant area of Siberia during daytime, does that mean that light never occurred in that area of Siberia?
Recently, the Pioneer spacecraft recorded the sound of interstellar space. No one ever heard this before. So does this mean that the sound of interstellar space only occurred for the first time in 2013, or has it been there all along and only now do we have the technology to hear it? The latter is correct.
As for the philosophical part of the question, this is best left to the Aristotle's of our time.

Lawrence Leffler, San Diego United States

No, their would be no sound or a tree or a forest. Everything is a figment of your imagination if you don't see it or hear it, then it does not exist in your reality

Tyler Goble, Annapolis, US

From a purely selfish point of view nothing exists unless I am there to observe it. That's what gives me life!

Phil Davis, Cheltenham UK

Many people do not see an issue with the question; I think this is due to the kind of minds these people have. Perhaps they possess mechanical minds as opposed to imaginative minds. Many years ago I found myself pondering if the material universe would exist if there was no conscious life present to experience it; on balance I concluded No, the material universe would not exist. Then I came across the tree question. My answer clearly is No, the tree did not make a sound. Please do not ask me to rationalise that answer - it is irrational, but so to is existence (of anything).

David, Wigan, UK

Of course! Just because it doesn't make sound from a larynx (vocal chords) doesn't mean there's no thud! Man u guys are wrong in the head!

Annie, Co. Kerry Ireland

To quote the great Forrest Gump: "I think that it may be both."

Chris Moles, United States

Dwell on this - if there was no conscious life would the physical universe still exist? Think deeply on this question and I believe you will have problems in answering either YES or NO.